1. Field of the Invention
The present invention relates to an ink jet printing apparatus and an ink jet printing method in which an image is printed using an ink tank that contains ink in a closed space so as to apply a negative pressure to the ink and a print head that can eject the ink fed from the ink tank.
2. Description of the Related Art
In an ink jet printing apparatus, ink with a negative pressure applied thereto is fed from an ink tank to a print head and then ejected through ejection ports in the print head using an ejection energy generating element such as an electrothermal transducing element (heater) or a piezo element. Such a printing apparatus is used in a narrow space, for example, on a checkout counter or in a shelf in a store or on a desk in an office. Thus, there has been a demand for a reduction in the size of the printing apparatus.
For a reduced size of the printing apparatus, ideally the print head and the ink tank are directly coupled together. Furthermore, to allow a large amount of ink to be contained while enabling a reduction in the size of the ink tank or the printing apparatus, a closed ink tank is advantageously used. In the closed ink tank described in Japanese Patent Laid-Open No. 2007-313711, a flexible bag containing ink is provided and biased, using a spring or the like, in a direction in which the internal volume of the bag is increased, to apply a negative pressure to the ink to be fed to the print head.
In the closed ink tank, the flexible bag containing ink forms a closed space that communicates only with the print head. Thus, for example, if the ink in the ink tank is exhausted to collapse the flexible bag with an amount of ink remaining in the print head, the negative pressure in the print head increases when the print head ejects the ink remaining inside the print head. This may preclude the ink from being appropriately ejected, leading to inappropriate image printing.